The present invention relates to a push button operating assembly or “push button actuator” of the type used in a variety of applications to operate an electrical switch, or to move a link to cause one or more latches to release so a closure can be opened, or to otherwise initiate or influence the operation of a device by causing an operating element of the device to move from one position to another.
More particularly, the invention relates to a push button actuator unit having a generally tubular housing which supports elements of a push button sub-assembly for translation in a housing-defined passage which extends along a central axis of the housing, wherein a disc-shaped member is mounted in a notch or slot of the housing that extends transverse to the axis, and wherein the disc-shaped member is used to regulate (i.e., limit, restrict, inhibit, resist or otherwise control) movement of selected elements of the push button sub-assembly. An optional locking mechanism may be included among the elements of the push button sub-assembly for selectively establishing and disestablishing a driving connection between front and rear elements of the push button sub-assembly to ensure that rearward extension of a rear element takes place in response to rearward depression of a front element only when the locking mechanism is unlocked.
Push button actuators of a variety of types have long been used to trip electrical switches, to release latches that hold closures in closed positions, and to initiate or otherwise influence the operation of various apparatus by causing operating elements of the apparatus to move from one position to another. Push button actuators used to release one or more latches that hold closures in closed positions typically include generally tubular housings that can be mounted on a closure or on structure extending about or adjacent to an opening that can be closed by the closure; and typically employ push button sub-assemblies which have elements that can move within central passages of their associated tubular housings. Each push button sub-assembly typically includes a front element that can be depressed rearwardly toward or into the central passage of a tubular housing to cause a rear element to extend rearwardly from the passage to move an operating element of a latch, or to move a link that releases plural latches.
If the push button actuator is to be “lockable,” a locking mechanism usually is included among the elements of the push button sub-assembly. Some lockable push button actuators prevent rearward movement of all elements of their push button sub-assemblies when locked. A drawback of push button actuators of this type is that their locking actions sometimes can be defeated by forcefully depressing elements of their push button sub-assemblies, for example by hammering.
To prevent defeat by hammering, some push button sub-assemblies employ locking mechanisms that drivingly connect their front and rear elements only when unlocked. By this arrangement, depression of a front element of the push button sub-assembly of an “unlocked” push button actuator will cause a rear element to move rearwardly to effect latch operation; but depression of the front element of the push button sub-assembly of a “locked” push button actuator unit will cause no rearward movement of a rear element and, therefore, should not cause latch operation even if front element depression is effected by hammering.
Regardless of whether any or all of the elements of a locked push button sub-assembly can be depressed, it may be possible to defeat the locking action of a push button actuator if front elements of the push button sub-assembly project sufficiently far forwardly from their associated housing passage to be gripped and turned by pliers, by a pipe wrench, or by some other tool or device that is capable of forcefully applying torque directly to these forwardly projecting elements. Likewise, it also may be possible to defeat the locking action of a push button actuator if a screwdriver, chisel or other flat-bladed tool can be inserted into a keyway of a front element and torqued with sufficient force to cause elements of the push button sub-assembly to turn to an unlocked or operated position, or to cause breakage of elements of the push button sub-assembly or other components of the push button actuator unit.
In an effort to provide key-lockable push button actuators that resist being defeated, when locked, by using tools such as pliers, pipewrenches, screwdrivers, chisels and the like to forcefully apply torque to push button sub-assembly elements, some proposals have provided push button sub-assemblies with elements that “free wheel” when forcefully torqued while locked. The addition of a “free wheeling” capability of this type is intended to enable locked push button sub-assembly elements that are forcefully torqued to rotate relative to their surrounding housings without causing push button operating mechanism breakage, and without causing the push button actuators to unlock, to operate, or initiate the operation of associated devices such as electrical switches or latches.
Although improvements have resulted as push button actuator unit designs have matured to provide enhanced resistance to hammering and defeat by overtorque force, problems and drawbacks remain that need to be addressed; and, in some instances, new designs have brought new problems and drawbacks that also need attention. To avoid defeat by hammering, many present-day push button actuator units employ sizable, heavy-duty components that are costly, difficult to manufacture, difficult to assemble and/or result in bulky units that are not well suited for use in applications where available space is restricted, for example, in tool boxes. Attempts to provide push button actuator units with sturdy “stop surfaces” that limit the forward-rearward movements of selected elements of push button sub-assemblies have, in some instances, generated multi-component solutions that are less than elegant. Some push button actuator unit proposals that employ push button sub-assembly elements which are designed to “free wheel” in response to overtorque cannot be fully or properly reset to return the units to normal operation after their push button sub-assembly elements have been forced even one time to “free wheel,” hence these units are designed to withstand only one overtorque experience that causes element free wheeling, whereafter the units require repair or replacement if normal operation is to be restored.